The Big Fall Cleanup. Or not?

 by Kelly Marshall, Markham Board Member, Garden Designer    

     In my front yard is a large fruitless Mulberry, and while I love it for the shade it provides, and the branches that are visited by woodpeckers, nuthatches, and cedar waxwings, this is the time of the year that I curse it, because it's shedding leaves in droves. Still, it probably won't be bare for several more weeks. In the meantime, it's a constant parade of falling leaves all day long, coming down and burying my walkway, and the many, many plants that make up my front yard.   (Those of you who may have visited my house on the Bringing Back the Natives tour in the past few years may remember that I don't have any grass-it's paths and plants, and plants and paths.

     Every year around this time, I try to unbury the smallest plants before they suffocate, shake off the mid-sized guys, and sweep the walkway every few days so visitors can actually see a path to my front door. And I wait. I know that we are destined to have a good winter storm sometime in December. And with a good winter storm, comes good winter winds. By the time I'm ready to do the big cleanup more than half of my leaves will have blown away. (Yes, possibly to my neighbors' yards, but more likely to join the leaves in the Oak Woodland that surrounds my neighborhood.) Unfortunately, that still leaves me with what seems like thousands to cleanup--by hand, because I have so many plants that a rake would be dangerous. I do leave smaller pieces in place to decompose.

     If you have any trees in your garden, you are probably experiencing the same thing right now. The question is, do we need to clean up the leaves, either with a rake or by hand, or could we simply leave them to break down and replenish the earth? As you can probably guess, it depends on the tree and what you've got beneath it.

     If your tree is above a lawn, it's usually fine, and even more sustainable to make a quick pass over the leaves with your lawnmower, and leave the tiny pieces to break down into the soil and add nutrients back in.

     If you have a lot of plants under your tree, do make sure that they aren't buried in leaves and debris, which can rot or smother the more tender plants. Also, keep in mind that piles of leaves can help insects hide. That can be good or bad-good because some bugs in your garden are the good kind. We want them around. Bad because, well, some bugs are the ones we'd like to move along. Last but not least, don't forget that bugs can be a food source for birds. No leaves equals fewer bug hiding places, and less food for birds looking for a winter meal.

     Here's how to handle some of our other popular trees and their Fall debris:

• Redwoods-Leave the needles in place below the tree. The Redwood duff that falls from the tree will decompose, creating a loamy, acidic soil that also helps our native understory plants thrive.
• Oaks-Debris from oaks is also called 'duff' and is best left in place. As it breaks down, it provides valuable nutrients back to the tree. I know it's tempting to clean it up, but if you are fortunate enough to have an Oak, try to do the best thing for it. They need their vitamins too. (Yes, I'm talking to you Pat M!)
• Sycamores, Beeches-Best left in place, again to decompose and provide organic matter back to the earth.
• Maples, Birch, Elm-Leaves can be left to decompose, but need to be chopped or mown into smaller pieces. Otherwise, they can form a mat that blocks air and water.

     By the way, if your tree is suffering from any kind of health problem, such as a fungus or powdery mildew, it's best to cleanup and destroy all leaves (i.e., into the green can) as they fall to prevent the spread of the disease.